1. Field of the Invention
This invention relates to the development of photo prints and is particularly applicable in the developing of diazo prints.
2. Description of the Prior Art
As shown for example in U.S. Pat. Nos. 3,702,096; 3,704,661; 3,704,662; 3,969,742 and 4,158,495, a system for developing prints has been created and commercialized in which the metering and application of developer liquid to the sensitized surface of the print paper is brought about by applying the developer liquid to the surface of an applicator roll which has a somewhat resilient microporous surface, and assuring the correct amount of liquid per unit area by applying a metering blade to the roll surface with a predetermined pressure. The roll is rotated and a sheet of exposed print paper, through the offices of a pressure blade, is fed into pressure contact with the portion of the roll surface having the metered deposit of developer. In this manner an accurately controlled developing action is brought about.
While machines using this type of developer application system have been in successful commercial operation for a number of years, it has been found that there is one aspect of their operation which could be made more convenient. This relates to the fact that after a copying machine has been shut down for an extended period and is started up its copy quality tends to suffer slightly unless the machine is allowed to idle for a run-in period of several minutes. The nature of this quality reduction is a nonuniformity of print density which appears as bands where the image is noticeably darker than in the areas between the bands. However, if the machine is allowed to run idle for a short period after start up, the condition is not present and the expected level of uniformity is obtained.
With respect to the obtaining of proper development, the attitude of the metering blade with reference to the surface of the applicator roll determines the amount of developer solution which will be presented per unit area to the surface of the copy sheet. This attitude is accordingly rather critical. Prior machines have included apparatus which permits adjusting the attitude of the metering blade, but this was a relatively permanent setting which required stopping and servicing the machine in order to effect an adjustment, i.e., this was more in the nature of a service adjustment than one in which the operation could perform to meet the needs of the immediate situation.